In addition, large clouds of dust and debris caused damage in several houses and a school nearby.
The top half of the crane collapsed and ended up twisting several times, though the reason for this was not known at press time.
A male worker lost his right leg, while a female colleague’s right heel was severed. Another male worker was found unconscious.
All of them have been hospitalised and contractor Songwuth Suwannasirikul and architect in charge Sakchai Phalangsuriya are being questioned by Din Daeng police, pending a decision whether they could be held responsible for the incident.
A man riding his motorcycle past the site said a 2-metre rod flew out and knocked him over.
“That was very close, I would be dead if it hit me,” said Maengtaek sae Tang, 64.
The 26-storey building, near the Asoke-Din Daeng intersection, is being built by TTS Engineering.
Din Daeng police said they were waiting for a report and an analysis on the cause of the accident from the district office.